Electrical tuning system



Jam?, 1930. F." A. KoLsTER `Lui-M039 ELECTRICAL TUNING SYSTEM y Fied Feb. 28, 1927 2 sheets-sheet 1 INVEN TOR.

Jap. 7, 1930. F. A. KoLsTER 1,743,039

i ELECTRICAL TUNING SYSTEM Filed Feb. 28. 1927 2 Sheets-Sheet 2 IN V EN TOR.

BY l f ATTORNEY Cra Patented `lan. 7, 1930 v UNITED STATES PATENT oFFice FREDERICK A. KOLSTER,.OF PALO ALTO, OALIFORNA, ASSIGNOR TELE- GRAPI-I COMPANY,' 0F SAN FRANCISCO, CALFORNIA, A CORPORATION OF CALI- FORNIA ELECTRICAL TUNING SYSTEM Application filed February 28, 1927. Serial No. 171,630.

My invention relates broadly to signal receiving apparatus and more particularly to a system of tuning in signal receiving circuits.

One of the objects of my invention is to provide a simplified tuning system for signal receiving circuits wherein micrometer adjustments in tuning may be effected with a minimum number of adjustable controls.

Another object of my invention is to pro vide an arrangement of variable capacity sys'- tem in association with a tuning inductance wherein adjustments in inductance values may be made simultaneously with an adjustment in capacity values for accurately tuning an electrical circuit to resonance at a selected frequency.

Another object of my invention is to provide a mounting of tuning inductor within an inductance coil where a pair of independent capacity areas are associated Vwith the tuning inductor withinthe in ductance coil in such position that for a shift in position of the inductor a change in the inductance and capacity values may be edected in a circuit associated with the several elements.

Another object of my invention is to provide a construction of coupling system for high frequency signal receiving circuits wherein a rotatable inductor may be shifted in position between a pair of stationary capacity areas located within one of the coupling inductances for effecting a change in the inductance and capacity values in an electrical circuit associated with the several elements for accurately tuning the circuit to a selected signaling frequency.

Other and further objects of my invention will be understood from the specification hereinafter following by reference to the accompanying drawings wherein Y. Figure l diagrammatically illustrates my invention as applied to a radio receiving system; Fig. 2 shows a modified circuit arrange* ment for a radio receiving system embodying the principles of my invention Fig. 3 illustrates a cross-sectional view ofa tuning inductance having the rotatable inductor and auxiliary capacity areas of my invention in association therewith; Fig. 4 is a longitudinal ceiving circuits for a selected signaling frei quency it has been proposed heretofore to employ an auxiliary variometer in the tuning circuit for minutely adjusting the frequency to which the circuit responds. The employy.

ment of the auxiliary variometer requires an additional control which is mechanically undesirable. The variometer is an added item of expense in a production program Which must be taken into account. By my present circuit arrangement and apparatus I provide a tuning inductor associatedV with a winding disposed in the input circuit of dio frequency amplification system. The winding is normally broadly tuned by a shunt connected variable condenser. The apparatus of my invention permits aline adjustment inn tuning after the circuits have been adj usted Tor a particular signaling' frequency. I provide a tuning inductor pivotally mounted f within an' inductance winding with auxiliary capacity areas whichl may be connected in various ways with the main variable capacity element for cooperation with the tuning inductorfor minutely increasing and decreasing the inductance or capacity values inthe tuning circuit.

Referring to the drawings in detail, reference character l designates anv antenna. sys.-

tem having a ground connectionQ with a primary system including primary inductance 3 adjustable by means ofa plurality of taps and cooperating switch 4. Secondary inductance 5 is coupledwith the primary inductance ,3 and'is tuned by means of variable condenser 1 6, the inductance 5 and condenser 6 constituting therinput circuit of a radio frequency amplifier and a detector system including electron tubes 7, 8, 9 and 10. A vcoupling transformer 1l is disposed between the output circuit of tube 7 and the input circuit of tube 8. The input circuit of tube 8 is tuned by means of variable condenser system 12.

The output circuit of tube 8 and the input circuit of tube 9 are coupled by means of'a transformer 14. VThe input circuit of tube 9 is tuned by-means of condenser system 15. The last stage of radio frequency amplificationis coupled to the electron tubedetector circuit through transformer system 16. The input circuit ofthe detector 10 is tuned by means ofvariable condenser 17. The del tector 10 may connect to any suitable' arrange-V ment of audiofrequency amplification apparatus and loud seaker systemdesignated generally at 18. ondensers 6, 12, 15 and 17 may be geared for simultaneous operation from a single control. The inductance' is supported by the insulated frame structureV 28 carried by brackets 29 from the panel structure 26. A shaft 22 is journaled within the supporting structure 28 and carries a rotatable disc or inductor 21 which maybe Amoved lfrom full line position to the dottedL line position 21 fory effecting adjustments in both the inductance and capacity values of the of rotatable shaft 22 withone of thecapacity input circuit constituted between winding 5 and variable condenserV 6. Auxiliary plates or capacity areas 23 and 24 are mounted within the Vframe'structure 28'on opposite sides areas disposed in a lanek above alongitudinal plane passingt rough the axis of the frame structure 28 andthe other of said capacityV areas located in a plane below a central plane passing through the axis of the winding. The inductor may be moved to selected positions under control of adjustable knob 25. I have shown the full line position of the inductor for illustrating the position for f' maximum inductance and maximum capacity Yso in the tuning circuit. When the inductor is moved to the .dotted line position 21'L apositionof minimum inductance and minimum cfipacity is obtained. Intermediate positions e ect different values of inductance and capacity in the tuning circuit. The eddy currents induced in the inductor 21 vary withvthe position of the inductor, and in that wayprovide a micrometer system and control for the inductance in the tuned circuit. The capacity is dependent upon the Vspacial relation between inductor 21 and capacity areas 23 and 24, the capacity being large for the full line position and relatively small for the dotted line position of the. inductor illustrated at 21".V vThe inductor may form one side of an auxiliary condenser system in shunt to the vmain condenser 6, as illustrated in Fig. 2, -while the. auxiliary plates 23 and 24 are be made and that no limitations uponmy invention are intended other than are imposed Y by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the-United Statesis as follows: i g

1. A tuning control system comprising a pair of coupled windings, a rotatable meta lic disc member journale'd on adiametricalaxis within one ofA said windings, and aY pair of fixed capacity areas positioned .within 'said windin g in planes parallel to the longitudinal axis thereof on opposite sides of'said rotate able metallic disc member, said rotatable metallic disc member being arranged to be varied in spacial relation with respect to said capacity areas for varying the effective capacity therebetween.

2. Atuning control system comprising a pair of coupled windings', a tuned circuit connected with one of saidwindings,a rotatable metallic disc member journaled on a diametrical axis within one of said windings, a pair of fixed capacity areas disposedwithin 'said last mentioned winding in planes parallel to the longitudinal axis of said windingA and connected with said tunedV circuit, said rotatable metallic disc member being variable in spacial relation with respect to said fixed capacity areas for adjusting the tuning of said circuit.

3. A tuning control system lcomprising an inductance, a tuned'circuit connected with said inductance, kmeans disposed within said inductance and connected with said 'tuned circuit for'varying the inductance and capacity values of said tuned circuit simultaneously, said means comprising a rotatable metallic disc member journaled Vdiametrically within said inductance and a pair of fixed capacity areas extending in planes parallel to the longitudinal axis of said inductance, said metallic disc member being arrangedto be moved to either of two limiting positions parallel to or perpendicular to said capacity areas for changing the inductance and capacity values Vof said circuit.`

4. A tuning control system comprising in combination with a tuned circuit including an inductance and shunt connected capacity, an auxiliary condenser disposed within said inductance, said auxiliary condenser being constituted by a plurality of plate members, one

of said plate members being movable within the field of said inductance for varying the effective value of said inductance and varying the effective vcapacity of said shunt connected condenser and the other plate members being rigidlyV mounted within said inductance in planes extending parallel to the longituvdinal axis of said inductance.

5. A tuning control system including an inductance and shunt connected variable condenser, an auxiliary condenser disposed within the field of said inductance and connected in shunt with said rst mentioned condenser, said auxiliary condenser havingl a portion thereof disposed in the center of said inductance and variable within the field of said inductance for changing the eective inductance and capacity values in said tuned circuit and other portions thereof extend ing in planes on each side of a central axis through said inductance.

6. A tuning circuit including' an inductance shunted by a variable capacity, an auxiliary condenser disposed within the field of said inductance and connected with 'said afore mentioned variable condenser, said auxiliary condenser having a pair of stationary plate members disposed in separate planes parallel with the longitudinal axis of said inductance, and a rotatable plate member disposed between said aforementioned plate member and movable from a position parallel to the axis of said inductance to a plane parallel to the direction of turns of said inductance for varying the effective inductance and capacity values in said tuning circuit.

' 7. A tuning circuit including an inductance shunted by a variable capacity comprising an auxiliary condenser constituted by a pair of plate members disposed within said inductance spaced one from the other in planes parallel to the longitudinal axis thereof, andv an inductor rotatable between said plate members from a position parallel to the axis of said inductance to a position parallel to the direction of the turns of said inductance for varying the inductance and capacity values in said tuning circuit from maximum to minimum over a selected range of frequencies.

In testimony whereof I aix my signature.

FREDERICK A. KOLSTER. 

